H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 202)

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• The system considers the ports in up state with the same port attributes and class-two configurations
as the reference port as candidate selected ports, and set all others in Unselected state.
• Static aggregation limits the number of Selected ports in an aggregation group. When the number
of the candidate selected ports is under the limit, all the candidate selected ports become Selected
ports. When the limit is exceeded, set the candidate selected ports with smaller port numbers in
Selected state and those with greater port numbers in Unselected state.
• If all the member ports are down, the system sets their states to Unselected.
A port that joins the aggregation group after the limit on the number of Selected ports has been reached
will not be placed in Selected state even if it should be in normal cases. This can prevent the ongoing
traffic on the current Selected ports from being interrupted. You should avoid the situation however, as
this may cause the Selected/Unselected state of a port to change after a reboot.
Dynamic aggregation mode
LACP is enabled on member ports in a dynamic aggregation group.
In a dynamic aggregation group,
• A Selected port can receive and transmit LACPDUs.
• An Unselected port can receive and send LACPDUs only if it is up and with the same configurations
as those on the aggregate interface.
In a dynamic aggregation group, the local system (the actor) negotiates with the remote system (the
partner) to determine the port state based on the port IDs on the end with the preferred system ID. In this
way, the system sets the ports to Selected or Unselected state. The following negotiation procedure
applies:
1. The system compares the system ID (comprising the system LACP priority and the system MAC
address) of the actor with that of the partner. The system with the lower LACP priority wins. If they
are the same, compare the system MAC addresses. The system with the smaller MAC address
wins.
2. The system compares the port IDs of the ports on the system with the smaller system ID. A port ID
comprises a port LACP priority and a port number. First, compare the port LACP priorities. The port
with the lower LACP priority wins. If two ports are with the same LACP priority, compare their port
numbers. The port with the smaller port number is selected as the reference port.
3. If a port in up state is with the same port attributes and class-two configuration as the reference port,
and the peer port of the port is with the same port attributes and class-two configurations as the
peer port of the reference port, the system considers the port as a candidate selected port.
Otherwise, the system sets the port to the Unselected state.
4. The number of Selected ports that an aggregation group can contain is limited. When the number
of candidate selected ports is under the limit, all the candidate selected ports are set to Selected
state. When the limit is exceeded, the system selects the candidate selected ports with smaller port
IDs as the Selected ports, and set other candidate selected ports to Unselected state. At the same
time, the peer device, being aware of the changes, also changes the state of its ports.
Guidelines
The following guidelines apply to static and dynamic aggregation modes:
• In an aggregation group, the port to be a Selected port must be the same as the reference port in
port attributes, and class-two configurations. To keep these configurations consistent, you should
configure the port manually.